ROBUSTNESS ANALYSIS ON SLIDING MODE CONTROL OF INDUCTION MOTOR

The aim of this paper is to establish that flux‐speed sliding mode control of induction machine is robust in the presence of saturation of magnetic core and rising resistance effects. Further, we show how to select the free control design parameters in order to maintain sliding mode regime. Simulation results are given to point out the good performances and the robustness of the studied control system. These simulations results are performed in the presence of hard disturbances represented by increasing of rotor resistances (by an amount 100%), and by decreasing stator and rotor inductance (respectively by an amount 25% and 50%)     

基于无源性的异步机自适应控制

对近年来出现的一种异步机控制方法--基于无源性的控制(简称PBC)进行了发展,从理论上取消了对定子电流反馈的要求,并针对转子电阻变化,增加了参数自调整的自适应控制和转子磁链闭环控制.该控制器保留了PBC方法的简单、无奇异点等优点,而且抑制了由于转子电阻变化引起的转速和磁链跟踪误差.     

AN ASYMPTOTIC SECOND‐ORDER SMOOTH SLIDING MODE CONTROL

Presented is a method of smooth sliding mode control design to provide for an asymptotic second‐order sliding mode on the selected sliding surface. The control law is a nonlinear dynamic feedback that in absence of unknown disturbances provides for an asymptotic second‐order sliding mode. Application of the second‐order disturbance observer in a combination with the proposed continuous control law practically gives the second‐order sliding accuracy in presence of unknown disturbances and discrete‐time control update. The piecewise constant control feedback is “smooth” in the sense that its derivative numerically taken at sampling rate does not contain high frequency components. A numerical example is presented.     

ON STABILITY AND PERFORMANCE OF INDUCTION MOTOR SPEED DRIVES WITH SLIDING MODE CURRENT CONTROL

A novel inner loop sliding mode current control scheme for induction motor speed drives is proposed in this paper. The controller design is based on the nonlinear mathematical model of an induction motor in a coordinate system oriented along the rotor flux. The parameters of the PI speed controller are taken into consideration in the inner loop sliding mode current control. Rigorous stability verification for the overall system is provided in this paper. The chattering in sliding mode control is attenuated using the reaching law design method. The experimental results show that the proposed approach exhibits robust tracking performance in the presence of motor parameter variations and load disturbances.     

NANO TRAJECTORY CONTROL OF MULTILAYER LOW‐VOLTAGE PZT BENDER ACTUATOR SYSTEMS

In this paper, nano trajectory control of the multilayer low‐voltage PZT (lead zirconate titanate) bender actuator system (MLVPZTBAS) is developed. System analyses in of the hysteresis characteristic, frequency response and sinusoidal response, were conducted to evaluate the system features. Because not all of the states of the MLVPZTBAS are directly available, an observer is required to estimate the states. The proposed scheme contains feedback linearization with a sliding‐mode controller and a state observer to estimate the system states of the MLVPZTBAS. The sliding‐mode control possesses an equivalent control and a switching control. To track a trajectory dominant by a specific frequency, a reference model consisting of desired amplitude and phase features is established. The equivalent control using the signals from the observer and the reference model is designed so as to produce the desired control behavior. Due to the existence of modeling and estimation errors, the switching control is then employed to achieve robust performance. Experiments on the MLVPZTBAS were carried out to verify the usefulness of the proposed control.     

模糊滑模控制和负载转矩补偿的异步电动机直接转矩控制

针对异步电动机(IM)转矩脉动以及抗干扰能力差的问题,设计了基于模糊滑模控制(FSMC)与负载转矩补偿的新型直接转矩控制(DTC),取代传统PID速度调节器的是一种滑模控制器.为解决滑模控制器中负载转矩脉动的问题,用模糊逻辑控制器取代了传统滑模控制律中的不连续部分,可以明显降低异步电动机在低速运转时的转矩脉动.提出了一种负载转矩观测器来估计未知的负载转矩.负载转矩观测器用来估计负载转矩扰动,估计作为速度环的前馈补偿.仿真结果表明:在低速负载转矩扰动时,该设计具有更好的动态响应和速度性能、更高鲁棒性和更强的抗干扰能力.     

A DUAL‐MODE ADAPTIVE ROBUST CONTROLLER APPLIED TO THE SPEED CONTROL OF A THREE‐PHASE INDUCTION MOTOR

This work presents a Dual‐Mode Adaptive Robust Controller applied to the angular shaft speed control of a three‐phase induction motor. A liaison between a Model Reference Adaptive Controller (MRAC) and a Variable Structure Model Reference Adaptive Controller (VS‐MRAC) through a tuning parameter is obtained using fuzzy logic. The basic idea of the Dual‐Mode controller is adding both the advantages of the VS‐MRAC transient behavior with the steady‐state properties of the conventional MRAC.     

采用新型控制方案的异步电动机变频调速微机仿人控制系统

本文主要研讨了交一直一交电流型逆变器异步电动机变频调速的微机控制系统。由于采用了原理简单的新型控制方案，且ＰＩ调节器引入仿人控制要求，使系统性能大大提高。作者在分析与计算的基础上，用ＣＭＣ－８０微机实现了对系统的控制，文中给出了软件设计中关键部分的程序框图，并附有实验波形。．     

A new non‐linear sliding‐mode torque and flux control method for an induction machine incorporating a sliding‐mode flux observer

In this paper a novel sliding‐mode control algorithm, based on the differential geometry state‐co‐ordinates transformation method, is proposed to control motor torque directly. Non‐linear feedback linearization theory is employed to decouple the control of rotor flux magnitude and motor torque. The advantages of this method are: (1) The rotor flux and the generated torque can be accurately controlled. (2) Robustness with respect to matched and mismatched uncertainties is obtained. Additionally, a varying continuous control term is proposed. As a result, chattering is eliminated without sacrificing robustness and precision. The control strategy is based on all motor states being available. In practice the rotor fluxes are not usually measurable, and a sliding‐mode observer is derived to estimate the rotor flux. The observer is designed to possess invariant dynamic modes which can be assigned independently to achieve the desired performance. Furthermore, it can be shown that the observer is robust against model uncertainties and measurement noise. Simulation and practical results are presented to confirm the characteristics of the proposed control law and rotor flux observer. Copyright © 2004 John Wiley & Sons, Ltd.     

REGIONAL STABILITY AND H∞ PERFORMANCE CONTROL OF AN INPUT‐SATURATED INDUCTION MOTOR VIA LMI APPROACH

In this paper, the robust speed control of an induction motor is investigated, and a parameter‐dependent model is addressed. The proposed scheme includes the feedback of states and the integral of the tracking error. In practice, considering the specification of the drive circuit, the saturation phenomenon of control signals is addressed. It is noted that the saturated signal is represented as a perturbed signal, which can be further investigated to determine the achieved robustness. Regional stability and H_∞ performance are discussed in this paper, where the derivations of feedback gains are formulated in terms of linear matrix inequalities (LMIs). To evaluate the control performances, a DSP‐based scheme for an induction motor was set up. Experimental results, associated with versatile command profiles and load conditions, show that the proposed system achieves satisfactory performance from the viewpoint of tracking accuracy and disturbance rejection.     

SECOND‐ORDER TERMINAL SLIDING MODE CONTROL OF INPUT‐DELAY SYSTEMS

This paper proposes a second‐order terminal sliding mode control for a class of uncertain input‐delay systems. The input‐delay systems are firstly converted into the input‐delay free systems and further converted into the regular forms. A linear sliding mode manifold is predesigned to represent the ideal dynamics of the system. Another terminal sliding mode manifold surface is presented to drive the linear sliding mode to reach zeros in finite time. In order to eliminate the chattering phenomena, a second‐order sliding mode method is utilized to filter the high frequency switching control signal. The uncertainties of the systems are analysed in detail to show the effect to the systems. The simulation results validate the method presented in the paper.     

基于模糊扰动观测器的PMSM积分滑模控制研究

为了克服传统永磁同步电机(Permanent magnet synchronous motor,PMSM)的滑模控制增益大容易产生抖振的问题,提出基于模糊观测器的PMSM积分滑模控制策略。采用新型趋近律设计积分滑模控制器取代传统的滑模控制器,提高系统的动态响应性能。结合模糊控制与自适应控制的特点,设计模糊扰动观测器,能够迅速有效地观测系统内部参数变化和外部扰动,并对积分滑模速度控制器进行前馈补偿,削弱系统抖振的同时提高了系统的鲁棒性。通过李雅普诺夫理论证明了该控制系统的稳定性。仿真及实验结果验证了该方法具有较强的鲁棒性,可以实现良好的跟踪效果并且无抖动。     

Disturbance observer–based adaptive boundary layer sliding mode controller for a type of nonlinear multiple‐input multiple‐output system

In this paper, a disturbance observer–based adaptive boundary layer sliding mode controller (ABLSMC) is proposed to compensate external disturbance and system uncertainty for a class of output coupled multiple‐input multiple‐output (MIMO) nonlinear systems. To show the effectiveness of the proposed ABLMSC, a traditional adaptive sliding mode controller (ASMC) is also designed. The stability of the closed‐loop system is examined by using the Lyapunov stability approach. The proposed control approach is implemented for a class of nonlinear output coupled MIMO systems. For real‐time validation, a coupled tank system is considered for study. Finally, simulation and real‐time results show that the proposed ABLMSC gives better performance such as reduced chattering and energy efficiency than that of the ASMC and some reported works in the literature.     

DYNAMICAL ADAPTIVE SLIDING MODE OUTPUT TRACKING CONTROL OF A CLASS OF NONLINEAR SYSTEMS

An alternative adaptive scheme to achieve output tracking for a class of minimum-phase dynamically input–output linearizable nonlinear systems with parametric uncertainties is considered. The proposed approach is based upon a combination of the adaptive backstepping design method and a sliding mode control (SMC) scheme to design dynamical adaptive sliding mode controllers and provide robust output tracking even in the presence of unknown disturbances. The validity of the proposed approach, regarding tracking objectives and robustness with respect to bounded stochastic perturbation inputs, is tested through digital computer simulations. © 1997 by John Wiley & Sons, Ltd.     

Observer‐based fault‐tolerant control of hypersonic scramjet vehicles in the presence of actuator faults and saturation

An adaptive sliding mode observer (SMO)–based fault‐tolerant control method taking into consideration of actuator saturation is proposed for a hypersonic scramjet vehicle (HSV) under a class of time‐varying actuator faults. The SMO is designed to robustly estimate the HSV states and reconstruct the fault signals. The adaptive technique is integrated into the SMO to approximate the unknown bounds of system uncertainties, actuator faults, and estimation errors. The robust SMO synthesis condition, which can be formulated as a set of linear matrix inequalities, is improved by relaxing structure constraints to the Lyapunov matrix. An anti‐windup feedback control law, which utilizes the estimated HSV states and the fault signals, is designed to counteract the negative effects of actuator saturation induced by actuator faults. Simulation results demonstrate that the proposed approach can guarantee stability and maintain performance of the closed‐loop system in the presence of HSV actuator faults and saturation.     

Predictive direct torque control with reduced ripples for induction motor drive based on T‐S fuzzy speed controller

Finite‐state model predictive control (FS‐MPC) has been widely used for controlling power converters and electric drives. Predictive torque control strategy (PTC) evaluates flux and torque in a cost function to generate an optimal inverter switching state in a sampling period. However, the existing PTC method relies on a traditional proportional‐integral (PI) controller in the external loop for speed regulation. Consequently, the torque reference may not be generated properly, especially when a sudden variation of load or inertia takes place. This paper proposes an enhanced predictive torque control scheme. A Takagi‐Sugeno fuzzy logic controller replaces PI in the external loop for speed regulation. Besides, the proposed controller generates a proper torque reference since it plays an important role in cost function design. This improvement ensures accurate tracking and robust control against different uncertainties. The effectiveness of the presented algorithms is investigated by simulation and experimental validation using MATLAB/Simulink with dSpace 1104 real‐time interface.     

INPUT‐STATE LINEARIZATION OF A ROTARY INVERTED PENDULUM

The aim of this paper is to design a nonlinear controller for the rotary inverted pendulum system using the input‐state linearization method. The system is linearized, and the conditions necessary for the system to be linearizable are discussed. The range of the equilibriums of the system is also investigated. Further, after the system is linearized, the linear servo controllers are designed based on the pole‐placement scheme to control the output tracking problem. The performance of the controller is studied with different system parameters. The computer simulations demonstrate that the controller can effectively track the reference inputs.     

SECOND‐ORDER NONSINGULAR TERMINAL SLIDING MODE DECOMPOSED CONTROL OF UNCERTAIN MULTIVARIABLE SYSTEMS

This paper proposes a second‐order nonsingular terminal sliding mode decomposed control method for multivariable linear systems with internal parameter uncertainties and external disturbances. First, the systems are converted into the block controllable form, consisting of an input‐output subsystem and a stable internal dynamic subsystem. A special second‐order non‐singular terminal sliding mode is proposed for the input‐output subsystem. The control law is designed to drive the states of the input‐output subsystem to converge to the equilibrium point asymptotically. Then the states of the stable zero‐dynamics of the system converge to the equilibrium point asymptotically. The method proposed in the paper has advantages for higher‐dimensional multivariable systems, in the sense that it simplifies the design and makes it possible to realize a robust decomposed control. Meanwhile, because of the adoption of the second‐order sliding mode, the control signal is continuous. Simulation results are presented to validate the design.     

Adaptive sliding‐mode control for Mars entry trajectory tracking with finite‐time convergence

This paper presents a novel adaptive sliding‐mode control (ASMC) method for Mars entry guidance and the finite‐time convergence in the presence of large uncertainties can be guaranteed. With the help of gain adaptive law, the nonoverestimating value of control gains can be achieved, and then, the chattering can be attenuated by the proposed ASMC method. Meanwhile, the extended state observer is introduced to estimate and compensate for uncertainties and the nonoverestimating problem is resolved further. In addition, the proposed method does not require any knowledge on the upper bound of uncertainty, which yields to be used in practical systems. Finally, the numerical simulation results are given to demonstrate the effectiveness of the proposed guidance law.     

A New Full‐Order Sliding Mode Observer Based Rotor Speed and Stator Resistance Estimation for Sensorless Vector Controlled Pmsm Drives

Sensorless control of a permanent magnetsynchronous motor (PMSM) at low speed remains a challenging task. In this paper, a sensorless vector control of PMSM using a new structure of a sliding mode observer (SMO) is proposed. To remove the mechanical sensors, a full‐order (FO‐SMO) is built to estimate the rotor position and speed of PMSM drives. The FO‐SMO, which replaces a sign function by a sigmoid function, can reduce the chattering phenomenon. In order to overcome time delay, we cancel the low pass filter. This sensorless speed control shows great sensitivity to stator resistance and system noise. To improve the robustness of sensorless vector control, a full‐order SMO technique has been used for stator resistance estimation. A novel stator resistance estimator is incorporated into the sensorless drive to compensate for the effects of stator resistance variation. The validity of the proposed FO‐SMO with a 1.1 kw low‐speed PMSM sensorless vector control is demonstrated by experiments. In this paper, experimental results for FO‐SMO, back‐EMF SMO and MRAS techniques were obtained with fixed point DSP‐based (TMS320F240).